Peanut components measured by ISAC: comparison with ImmunoCap and clinical relevance in peanut allergic children

Abstract

Background Specific IgE (sIgE) against the peanut component Arachis hypogaea (Ara h) 2 has been shown to be the most important allergen to discriminate between peanut allergy and peanut tolerance. Several studies determined sIgE cut off values for Ara h 2, determined by singleplex measurements. However, cut off values for Ara h 2 from multiplex arrays are less well defined. The aim of this study was to evaluate the correlation between Ara h 2 sIgE determined by singleplex versus multiplex measurements and to assess the diagnostic value of the different peanut components included in Immuno Solid-phase Allergen Chip (ISAC) multiplex analysis in children with a suspected peanut allergy. Methods In this retrospective study we analyzed Ara h 2 sIgE values with singleplex Fluorescence Enzyme Immunoassay (FEIA, ImmunoCap) and multiplex microarray (ISAC) measurements in 117 children with a suspected peanut allergy. Also, other peanut components measured by ISAC were analyzed. Double blinded placebo controlled oral food challenges were used as golden standard. Results Among all studied peanut components FEIA Ara h 2 sIgE showed the highest area under the curve (AUC, 0.922), followed by ISAC Ara h 6 and Ara h 2 sIgE with AUCs of respectively 0.906 and 0.902. Best cut off values to diagnose peanut allergy were 4.40 kU/l for FEIA Ara h 2 sIgE and, 7.43 ISU and 8.13 ISU for respectively Ara h 2 and Ara h 6 sIgE in ISAC microarray. Ara h 2 sIgE determined in FEIA and ISAC showed a good correlation (r = 0.88; p < 0.01). Conclusion Ara h 6 and Ara h 2 sIgE in multiplex ISAC are both good predictors of clinical peanut allergy in Dutch children, and their performance is comparable to the use of Ara h 2 in singleplex FEIA. The simultaneous measurement of different peanut components using ISAC is an advantage and clinically useful to detect peanut allergic children that are Ara h 2 negative but sensitized to other peanut proteins such as Ara h 6.

Diagnostic accuracy of the ALEX2 test in peanut‐sensitized children

“…Similarly, in the ISAC IgE-microarray, the optimal cut-off value for Ara h 2 was 0.81 ISU with a sensitivity and specificity of 86% and 82%, respectively. 7 Those results are in accordance with a recently published systematic review of paediatric studies where Ara h 2 sIgE with a cut-off of 0.35 kU/L (ImmunoCAP) was reported to have a sensitivity of 85.8% (95% CI 79.3-90.6) and a specificity of 83.6% (95% CI 76.0-89.2). 8 We found that the combination of Ara h 2, Ara h 6 and SPT had the best accuracy (90.9%) with the highest LR+ (22.2).…”

“…When using the optimal cut‐off for Ara h 2 (0.83 kUA/L), the high sensitivity was maintained, while specificity slightly increased to 89.1%. Similarly, in the ISAC IgE‐microarray, the optimal cut‐off value for Ara h 2 was 0.81 ISU with a sensitivity and specificity of 86% and 82%, respectively 7 . Those results are in accordance with a recently published systematic review of paediatric studies where Ara h 2 sIgE with a cut‐off of 0.35 kU/L (ImmunoCAP) was reported to have a sensitivity of 85.8% (95% CI 79.3–90.6) and a specificity of 83.6% (95% CI 76.0–89.2) 8 …”

Invariant NKT cells are more abundant in peanut-allergic adults and a subset of CD8+ iNKT cells are depleted after peanut oil exposure

“…Different exposure routes can lead to peanut allergy, with primary peanut allergy occurring from sensitization to peanut only and peanut allergy due to cross reactivity with tree or grass pollen (secondary allergy), which is typically associated with milder oral allergy symptoms. To establish if a person is peanut allergic and distinguish if they have primary or secondary peanut allergy, it can be advantageous to measure IgE to multiple peanut components (17). Access to a multiplex diagnostic array was not available for this study, but subjects' levels of IgE against both Ara h 2 and Ara h 8 were measured.…”

Update on In Vitro Diagnostic Tools and Treatments for Food Allergies

“…Even so, the levels of Ara h 2 were comparable to the levels obtained with ImmunoCAP. They concluded that the different peanut components using ISAC was an advantage and clinically useful to detect peanut allergic children [35]. It has been published that the sIgE levels measured with ISAC (Act d 1, Act d 2) showed a sensitivity (59.5%) similar to that of ImmunoCAP (with whole kiwi extract, 63.9%).…”

“…Milk [56] High throughput Need to improve the Sesame [32] Hazelnut [33] Peanut allergic children [35] Kiwi [36] LTP (Multiple Food) [38] Egg white and yolk [39] Standardized High throughput Can be automatized Poor in detection of sensitization from clinically reactive FA.…”